Electrodeless Lamps with Grounded Coupling Elements

ABSTRACT

An electrodeless plasma lamp includes a bulb containing a gas-fill and light emitter(s) excited to produce light using radio-frequency (RF) energy. Input and output coupling elements separated from each other by a gap couple RF energy from an RF source to the bulb. One end of the input coupling element is electrically connected to an RF source while the other end is connected to ground. One end of the output coupling element is connected to ground while the other end is connected to the bulb.

CROSS REFERENCE TO RELATED APPLICATIONS

This patent application is a continuation-in-part of U.S. Ser. No.12/685,650, filed Jan. 11, 2010, which is a continuation-in-part of U.S.Ser. No. 12/484,933 filed Jun. 15, 2009, which claims priority to U.S.Provisional Application No. 61/075,735, filed Jun. 25, 2008, commonlyassigned, all of which applications are hereby incorporated byreference.

BACKGROUND OF THE INVENTION

This invention is directed to devices and methods for generating lightwith plasma lamps. More particularly, the present invention provides aplasma lamp driven by a radio-frequency source without the use ofelectrodes inside the bulb. Such plasma lamps can be applied to lightingapplications for stadiums, parking lots, military and defense, streets,buildings, vehicle headlamps, aircraft landing lights, bridges, uv watertreatment, agriculture, architectural lighting, stage lighting, medicalillumination, microscopes, projectors and displays, as well as otheruses.

Plasma lamps provide extremely bright, broadband light, and are usefulin many applications, such as general illumination, projection systems,and industrial processing. The typical plasma lamp manufactured todaycontains a mixture of gas and trace substances that are excited to forma plasma using a high current passed through closely-contactingelectrodes. This arrangement, however, suffers from deterioration of theelectrodes inside the bulb, and therefore a limited lifetime. Otherlimitations also exist with conventional plasma lamps.

From the above, it is seen that techniques for improving plasma lampsare highly desirable.

BRIEF SUMMARY OF THE INVENTION

According to the present invention, techniques directed to devices andmethods for generating light with plasma lamps are provided. Moreparticularly, the present invention provides plasma lamps driven by aradio-frequency source without the use of electrodes inside the gasfilled vessel (bulb). In one implementation, the radio-frequency sourceis coupled to the gas filled vessel using a compact airresonator/waveguide with grounded coupling elements. In someembodiments, the resonator/waveguide is not made using, and is generallyfree from a dielectric material, such as alumina or quartz. In additionthe arc of the gas filled vessel (bulb) is not substantially surroundedby the body of the resonator/waveguide, thus allowing the use ofreflectors and other optical components used in designing luminaires.The gas filled vessel is includes the arc, which is substantially freefrom any mechanical blockage by the body of the resonator waveguide,which allows the use of reflectors and other optical components.

In a specific embodiment, the present invention provides anelectrodeless plasma lamp. The lamp includes an input coupling elementand an output coupling element. One end of the input coupling element iselectrically connected to the output of an RF source. The RF sourceconsists of an RF oscillator and one or more stages of amplifiers, or itcan consist of a high power oscillator. The other end of the inputcoupling element is electrically connected to ground (or is at RF groundpotential). One end of the output coupling element is also connected toground, or is at RF ground potential, and the other end of the outputcoupling element is connected to the gas filled vessel. A gap betweenthe input coupling element and output coupling element provides forapplication of RF energy. By adjusting the dimensions of the input andoutput coupling elements and the gap between them, one can maximize theRF energy coupled to the bulb. The coupling elements can be surroundedby a conductive enclosure (lamp body) having a surface at groundpotential. The inside of the enclosure is filled with air, other gases,or alternatively is in vacuum.

In a preferred embodiment a substantial portion of the bulb extendsoutside the enclosure through a hole in the enclosure. RF energy couplesto the bulb capacitively, or inductively, or a combination ofcapacitively and inductively. RF energy ionizes the gas inside the bulband vaporizes the light emitter(s) resulting in electromagneticradiation from the bulb in the visible, ultraviolet and/or infraredspectrum. The lamp may further include a reflector to direct theluminous output of the bulb. The lamp further may include a ground strapto conductively connect to, or be coupled to, the top of the bulb andthe conductive lamp body. Alternatively, the ground strap mayconductively connect the top of the bulb-coupling element assembly tothe reflector, which in turn is conductively connected to the lamp body.

In another embodiment, the lamp body comprises a metallic conductivebody partially filled with a dielectric insert. The dielectric insertmay be a single material, layered, a composite, or other suitablespatial configurations and/or materials. Alternatively, the lamp bodycan be filled with a dielectric material such as alumina.

In a specific embodiment, the present invention provides an alternativeelectrodeless plasma lamp. The lamp includes a gas filled vessel (bulb),an input coupling element and an output coupling element separated fromthe input coupling element by a gap. The gas filled vessel having atransparent or translucent body configured by an inner region and anouter surface region with a cavity being defined within the innerregion. The gas filled vessel typically contains an inert gas such asArgon or Xenon (or combination of inert gases) and one or more lightemitters such as Mercury, Indium Bromide, Sulfur, Cesium Bromide, orother elements. One end of the output coupling element is connected tothe gas filled vessel and the other end of the output coupling elementis electrically connected to ground or to a conductive enclosuresurrounding the coupling elements (lamp enclosure) which is at groundpotential. The input coupling element couples RF energy to the outputcoupling element. One end of the input coupling element is electricallyconnected to an RF source, including an oscillator and an amplifier. Theother end of the input coupling element is connected to ground or to theconductive enclosure surrounding the coupling elements (lamp enclosure)which is at ground potential. The dimensions of the input and outputcoupling elements and the gap between them can be adjusted to optimizeRF energy transfer between the RF source and the gas filled vessel. RFenergy ionizes the gas inside the bulb and vaporizes the lightemitter(s) resulting in electromagnetic radiation from the bulb in thevisible and/or ultra violet and/or infrared part of the spectrum.

The present lamp is compact and can be configured inside conventionalluminaires, such as luminaires used for street lighting and parking lotlighting. Furthermore, the lamp can be configured to have an exposed arcto allow use of conventional optical components, such as aluminumreflectors. The present lamp can also be manufactured more efficientlyand at lower cost than the conventional dielectric resonators, such asthose described in U.S. Pat. No. 6,737,809B2. That is, the electrodelesslamp with grounded coupling elements is significantly lower in cost andsimpler to manufacture since it does not require precise control of thedepth of probes. Furthermore, the lamp can be configured to have anexposed arc to allow use of conventional optical components. Furtherdetails of the present invention can be found throughout thespecification below. The present invention achieves these benefits andothers in the context of known process technology.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the present invention and itsadvantages will be gained from a consideration of the followingdescription of preferred embodiments, read in conjunction with theaccompanying drawings. In the figures and description, numerals indicatevarious features of the invention, and like numerals referring to likefeatures throughout both the drawings and the description.

FIG. 1A is a simplified drawing of an embodiment of the presentinvention with one end of the input transmission line (input couplingelement) connected to an RF source while the other end of the inputtransmission line is electrically connected to ground. The inputtransmission line couples RF energy to the output transmission line(output coupling element) that is electrically connected to ground onone end of the output transmission line and couples the RF energy to thegas filled vessel (bulb) at the other end.

FIG. 1B is a simplified drawing of an embodiment of the presentinvention similar to the one shown in FIG. 1A. In this embodiment theinput transmission line (input coupling element) and the outputtransmission line (output coupling element) are electrically connectedto ground through capacitors. The capacitors are selected to provide alow impedance connection to ground at the frequency of the RF source.The capacitors provide an open circuit at DC.

FIG. 2A is a simplified drawing of another embodiment of the presentinvention. It is similar to the one shown in FIG. 1A except that theinput transmission line (input coupling element) and part of the outputtransmission line (output coupling element) are replaced by spiralinductors.

FIG. 2B is a simplified drawing of another embodiment of the presentinvention. It is similar to the one shown in FIG. 2A except that theinput coupling element and the output coupling element are electricallyconnected to ground through capacitors. The capacitors are selected toprovide a low impedance connection to ground at the frequency of the RFsource. The capacitors provide an open circuit at DC.

FIG. 2C is a simplified drawing of another embodiment of the presentinvention. It is similar to the one shown in FIG. 2A except that theinput coupling element (spiral inductor) couples RF energy to the outputcoupling element (spiral inductor) by wrapping around it.

FIG. 3A is a simplified perspective view of another embodiment of thepresent invention. The input coupling element is connected to an RFsource at one end and the other end of the coupling element iselectrically connected to ground. The input coupling element couples RFenergy to an output coupling element that is electrically connected atone end to the ground and the other end couples RF energy to gas filledvessel (bulb).

FIG. 3B is a cross-sectional perspective view of the lamp in FIG. 3Awithout the RF source. It illustrates the input and output couplingelement with a coupling gap between them.

FIG. 4A is a simplified cross-sectional view of the embodiment shown inFIG. 3A.

FIG. 4B is a simplified drawing of another embodiment of the presentinvention. It is similar to the embodiment shown in FIG. 4A except thatthe input coupling element and output coupling elements are electricallyconnected to ground through capacitors. The capacitors are selected toprovide low impedance connections to ground at the frequency of the RFsource. The capacitors provide an open circuit at DC.

FIG. 4C illustrates another embodiment of the invention shown in FIG.4A. In this embodiment a feedback coupling element is added and anamplifier connected between the feedback coupling element and the inputcoupling element providing for frequency selective oscillation in thefeedback loop.

FIG. 4D shows another embodiment of the invention shown in FIG. 4A. Inthis embodiment the top of the gas filled vessel (bulb) is electricallyconnected to the lamp body via wires or straps and a top couplingelement.

FIG. 4E shows another embodiment of the invention shown in FIG. 4D. Inthis embodiment an electrically conductive ring (“halo”) is used alongthe length of the gas filled vessel (bulb) to give additional controlover the plasma (arc) inside the bulb. This electrically conductive ringis connected to the lamp body via wires or straps.

FIG. 4F shows another embodiment of the present invention. It is similarto the embodiment in FIG. 4A but in this case the lamp body does notnecessarily have rectangular edges and can take other forms to containthe input and output coupling elements.

FIG. 5A shows another embodiment of the present invention. It is similarto the embodiment in FIG. 4A but in this case the lamp body is filledwith a dielectric material such as alumina or quartz instead of air.

FIG. 5B shows another embodiment of the present invention. It is similarto the embodiment in FIG. 5A but in this case the lamp body does nothave a “neck” region and part of the arc of the gas filled vessel (bulb)is inserted into dielectric material.

FIG. 5C shows another embodiment of the present invention. It is similarto the embodiment in FIG. 5B but in this case the bulb is outside thedielectric material of the lamp body and the arc of the gas filledvessel (bulb) is not surrounded by the lamp body. The size of the lampbody can be made to be much more compact.

FIG. 5D shows another embodiment of the invention shown in FIG. 5C. Inthis embodiment the top of the gas filled vessel (bulb) is electricallyconnected to the lamp body via wires or straps and a top couplingelement.

FIG. 5E shows another embodiment of the invention shown in FIG. 5C. Inthis embodiment an electrically conductive ring (“halo”) is used alongthe length of the gas filled vessel (bulb) to give additional controlover the plasma (arc) inside the bulb. This electrically conductive ringis connected to the lamp body via wires or straps.

FIG. 5F shows another embodiment of the present invention. It is similarto the embodiment in FIG. 5A but in this case the lamp body does notnecessarily have rectangular edges and can take other forms to containthe input and output coupling elements.

FIG. 6A shows another embodiment of the present invention. It is similarto the embodiment in FIG. 4A but in this case the output couplingelement is surrounded by a dielectric sleeve made from a material suchas quartz.

FIG. 6B shows another embodiment of the present invention. It is similarto the embodiment in FIG. 6A but in this case a dielectric sleeve madefrom a material such as quartz surrounds the output coupling elementonly in the top portion (neck portion) of the lamp body.

DETAILED DESCRIPTION OF THE INVENTION

According to the present invention, techniques directed to devices andmethods for generating light with plasma lamps are provided. Moreparticularly, the present invention provides plasma lamps driven by aradio-frequency source without the use of electrodes inside a gas-filledvessel.

The following description is presented to enable one of ordinary skillin the art to make and use the invention and to incorporate it in thecontext of particular applications. Various modifications, as well as avariety of uses in different applications will be readily apparent tothose skilled in the art, and the general principles defined herein maybe applied to a wide range of embodiments. Thus, the present inventionis not intended to be limited to the embodiments presented, but is to beaccorded the widest scope consistent with the principles and novelfeatures disclosed herein.

In the following detailed description, numerous specific details are setforth in order to provide a more thorough understanding of the presentinvention. However, it will be apparent to one skilled in the art thatthe present invention may be practiced without necessarily being limitedto these specific details. In other instances, well-known structures anddevices are shown in block diagram form, rather than in detail, in orderto avoid obscuring the present invention.

The reader's attention is directed to all papers and documents which arefiled concurrently with this specification and which are open to publicinspection with this specification, and the contents of all such papersand documents are incorporated herein by reference. All the featuresdisclosed in this specification, (including any accompanying claims,abstract, and drawings) may be replaced by alternative features servingthe same, equivalent or similar purpose, unless expressly statedotherwise. Thus, unless expressly stated otherwise, each featuredisclosed is one example only of a generic series of equivalent orsimilar features.

Furthermore, any element in a claim that does not explicitly state“means for” performing a specified function, or “step for” performing aspecific function, is not to be interpreted as a “means” or “step”clause as specified in 35 U.S.C. Section 112, Paragraph 6. Inparticular, the use of “step of” or “act of” in the claims herein is notintended to invoke the provisions of 35 U.S.C. 112, Paragraph 6.

Please note, if used, the labels left, right, front, back, top, bottom,forward, reverse, clockwise and counter clockwise have been used forconvenience purposes only and are not intended to imply any particularfixed direction. Instead, they are used to reflect relative locationsand/or directions between various portions of an object. Additionally,the terms “first” and “second” or other like descriptors do notnecessarily imply an order, but should be interpreted using ordinarymeaning.

As background for the reader, we would like to describe conventionallamps and their limitations that we discovered. Electrodeless plasmalamps driven by microwave sources have been proposed. Conventionalconfigurations include a gas filled vessel (bulb) containing Argon and alight emitter such as Sulfur or Cesium Bromide (see for example, U.S.Pat. No. 6,476,557B1). The bulb is positioned inside an airresonator/waveguide with the microwave energy provided by a source suchas a magnetron and introduced into the resonator/waveguide to heat andionize the Argon gas and vaporize the Sulfur to emit light. To use RFsources that are efficient and low-cost it is desirable to design theresonator/waveguide to operate at frequencies below approximately 2.5GHz and preferably below 1 GHz. A conventional air resonator/waveguideoperating in the fundamental resonant mode of the resonator at 1 GHz hasat least one dimension that is approximately 15 cm long since thislength is about half the free-space wavelength (lambda/2) of theresonant frequency of the resonator. This results in limitations thatwere discovered. Such limitations include a resonator/waveguide sizethat is too large for most commercial lighting applications since theresonator/waveguide will not fit within typical lighting fixtures(luminaires). In addition since the bulb was placed inside theair/resonator cavity, the arc of the bulb is not accessible for use inthe design of reflectors for various types of luminaires used incommercial and industrial lighting applications.

In the configuration proposed in U.S. Pat. No. 6,737,809B2, Espiau, etal., the air inside the resonator is replaced with alumina resulting inreducing the size of the resonator/waveguide since the free-spacewavelength (fundamental mode guided wavelength for thisresonator/waveguide) is now reduced approximately by the square-root ofthe effective dielectric constant of the resonator body. This approachhas some advantages over the air resonator in U.S. Pat. No. 6,476,557B1by reducing the size of the resonator but it has its own drawbacks. Suchdrawbacks may include higher manufacturing costs, losses associated withthe dielectric material, and blockage of light from the bulb by thedielectric material. In this approach, the arc of the bulb is notaccessible either limiting its use in various types of luminaires usedin commercial and industrial lighting applications.

FIG. 1A is a simplified drawing of an embodiment of the presentinvention with one end of the input transmission line (input couplingelement) 310 made from an electrically conductive material such asCopper is connected to an RF source while the other end of the inputtransmission line is electrically connected to ground 200. The RF sourceconsists of an oscillator 205 and an RF amplifier 210 with the output ofthe oscillator connected to the input 212 of the RF amplifier 210 andthe output of the amplifier 211 is conductively connected to the inputcoupling element 310. The amplifier can consist of multiple stages ofamplification. The input coupling element is separated from the outputtransmission line (output coupling element) 320, which is also made froman electrically conductive material such as Copper, by a coupling gap330. The output coupling element is electrically connected to ground 201at one end and is connected to the gas filled vessel 130 which containsthe plasma arc 115 at the other end. The input transmission line couplesRF energy to the output transmission line which in turn couples the RFenergy to the gas filled vessel (bulb) capacitively, inductively, orcombination of capacitively and inductively. By adjusting the dimensionsof the input and output coupling elements as well as the gap betweenthem one can maximize the transfer of the RF power between the RF sourceand the bulb. The bulb is made of a suitable material such as quartz ortranslucent alumina or other transparent or translucent material. Thebulb is filled with an inert gas such as Argon or Xenon and a lightemitter such as Mercury, Sodium, Dysprosium, Sulfur or a metal halidesalt such as Indium Bromide, Scandium Bromide, Thallium Iodide, HolmiumBromide, Cesium Iodide or other similar materials (or it cansimultaneously contain multiple light emitters). RF energy is coupledcapacitively, or inductively, or a combination of inductively andcapacitively, by the output coupling-element 320 to the bulb 130,ionizing the inert gas and vaporizing the light emitter(s) resulting inintense light emitted from the lamp. The majority of the arc of the bulb115 is not blocked by the coupling element allowing efficient lightcollection by reflectors. Even though a microstrip type transmissionline is shown in FIG. 1A other types of RF transmission lines can beused. The transmission lines can be inside a conductive enclosure andcan also be integrated as part of the amplifier circuit. This diagram ismerely example, which should not unduly limit the scope of the claimsherein. One of ordinary skill in the art would recognize othervariations, alternatives, and modifications.

FIG. 1B is a simplified drawing of an embodiment of the presentinvention similar to the one shown in FIG. 1A. In this embodiment theinput transmission line (input coupling element) 310 and the outputtransmission line (output coupling element) 320 are electricallyconnected to ground 200 and 201 through capacitors 330 and 340respectively. The capacitors 330 and 340 are selected to provide a lowimpedance connection to ground at the frequency of the RF source. Thecapacitors provide an open circuit at DC.

FIG. 2A is a simplified drawing of another embodiment of the presentinvention. It is similar to the one shown in FIG. 1A except that theinput transmission line (input coupling element) 310 is replaced by aspiral inductor 360. One end of the spiral inductor 360 is electricallyconnected to the output 211 of the RF power 210 and the other end of thespiral inductor is connected to ground 200. An oscillator 205 isconnected to the input 212 of the RF power amplifier. The amplifier canconsist of multiple stages of amplification. Part of the outputtransmission line (output coupling element) 320 is also replaced by aspiral inductor 370. One end of the spiral inductor (part of the outputcoupling element) 370 is electrically connected to ground 201 while theother end is connected to transmission line 321 (also part of outputcoupling element). The transmission line 321 is connected on one end tospiral inductor 370 and on the other end it is connected to the gasfilled vessel 130 which contains the plasma arc 115. The input couplingelement 360 couples RF energy to the output coupling elements 370 and321 which in turn couple the RF energy to the gas filled vessel (bulb)capacitively, inductively, or combination of capacitively andinductively. By adjusting the dimensions (diameter, length, number ofturns, etc. of the spiral inductors) of the input and output couplingelements as well as the gap 335 between them one can maximize thetransfer of the RF power between the RF source and the bulb.

FIG. 2B is a simplified drawing of another embodiment of the presentinvention similar to the one shown in FIG. 2A. In this embodiment theinput spiral inductor (input coupling element) 360 and the output spiralinductor 370 and transmission line 321 (output coupling elements) areelectrically connected to ground 200 and 201 through capacitors 330 and340 respectively. The capacitors 330 and 340 are selected to provide alow impedance connection to ground at the frequency of the RF source.The capacitors provide an open circuit at DC.

FIG. 2C is a simplified drawing of another embodiment of the presentinvention. It is similar to the one shown in FIG. 2A except that theinput coupling element (spiral inductor) 380 couples RF energy to theoutput coupling element (spiral inductor) 370 by wrapping around it. Byadjusting the dimensions (diameter, length, number of turns, etc. of thespiral inductors) of the input and output coupling elements as well asthe overlap and spacing between them one can maximize the transfer ofthe RF power between the RF source and the bulb.

FIG. 3A is a simplified perspective view of another embodiment of thepresent invention. This diagram is merely example, which should notunduly limit the scope of the claims herein. One of ordinary skill inthe art would recognize other variations, alternatives, andmodifications. The lamp consists of a lamp housing 600 made from anelectrically conductive material that surrounds the input and outputcoupling elements. This conductivity may be achieved through theapplication of a conductive veneer, or through the choice of aconductive material. An example embodiment of conductive veneer issilver paint or alternatively the lamp body can be made from sheet ofelectrically conductive material such as Aluminum. In this embodimentthe lamp body consists of a wider diameter bottom section 625 and anarrower diameter 650 top section and is filled with air 601 or othergases such as Nitrogen or fluids, or can be a vacuum. A cylindrical lampbody is depicted, but rectangular or other shapes may be used. The inputcoupling element 630 is connected to the lamp body at the top surface631 (which is at ground potential 200) and at the other end is connectedto an RF connector 611 through an opening in the lamp body 610. Theinput coupling element 630 can be made from a solid or hollow conductoror alternatively from a dielectric material with an electricallyconductive coating. The RF source consists of an oscillator 205electrically connected to the input 212 of the power amplifier 210 andthe output of the power amplifier 211 is electrically connected to RFconnector 611. The amplifier can consist of multiple stages ofamplification. The input coupling element 630 couples RF energy to theoutput coupling element 120 and the two coupling elements are separatedby a coupling gap 350. The output coupling element 120 is connected tothe lamp body at the bottom 605 (which is at ground potential 201) andat the other end is connected to the gas filled vessel (bulb) 130. Theoutput coupling element can be made from solid or hollow electricallyconductive material or alternatively can be made from a dielectricmaterial with an electrically conductive coating. The top end of theoutput coupling element is shaped to closely receive the gas filledvessel. In the case that the output coupling element is made from asolid conductor a thin layer of a dielectric material or refractorymetal is used as an interface barrier between the bulb and the outputcoupling element. The output coupling element is separated from the topportion of the lamp body 650 by a gap 140. By adjusting the dimensionsof the input and output coupling elements as well as the dimensions ofthe lamp body including the size of the gaps 350 and 140, one canmaximize the transfer of the RF power between the RF source and thebulb. In a specific embodiment, the gas filled vessel is made of asuitable material such as quartz or translucent alumina or othertransparent or translucent material. The gas filled vessel is filledwith an inert gas such as Argon or Xenon and a light emitter such asMercury, Sodium, Dysprosium, Sulfur or a metal halide salt such asIndium Bromide, Scandium Bromide, Thallium Iodide, Holmium Bromide,Cesium Iodide or other similar materials (or it can simultaneouslycontain multiple light emitters). RF energy is coupled capacitively, orinductively, or a combination of inductively and capacitively, by theoutput coupling-element 120 to the bulb 130, ionizing the inert gas andvaporizing the light emitter(s) resulting in intense light emitted fromthe lamp. The majority of the arc of the bulb 115 in this embodiment isnot surrounded by the walls of the lamp body.

In one example embodiment, the bottom 625 of the lamp body 600 mayconsist of a hollow aluminum cylinder with a 5 cm diameter, and a heightof 3.8 cm and the top portion 650 has a diameter of 1.6 cm and a heightof 1.4 cm. The diameter of the input coupling element 630 is about 0.13cm and the diameter of the output coupling element 120 is about 0.92 cm.The fundamental resonant frequency of such lamp body is approximately900 MHz. By adjusting the various design parameters (dimensions of thelamp body, length and diameter of the output coupling element, gapbetween the input and output coupling element, gap between the outputcoupling element and the walls of the lamp body) as well as otherparameters it is possible to achieve different resonant frequencies.Also it is possible by adjusting various design parameters to havenumerous other design possibilities for a 900 MHz resonator. Onesignificant advantage of the invention is that the input couplingelement 630 and the output coupling element 120 are respectivelygrounded at planes 631 and 605, which are coincident with the outersurface of the lamp body 600. This eliminates the need to fine-tunetheir depth of insertion into the lamp body—as well as any sensitivityof the RF coupling between them to that depth—simplifying lampmanufacture, as well as improving consistency in lamp brightness yield.This illustration is merely an example, which should not unduly limitthe scope of the claims herein. One of ordinary skill in the art wouldrecognize other variations, modifications, and alternatives.

FIG. 3B is a cross-sectional perspective view of the lamp in FIG. 3Awithout the RF source. The input coupling element 630 is shown connectedto the top surface 631 of the conductive lamp body 600. The outputcoupling element 120 in this case is made from a solid conductor and isscrewed into the bottom of the conductive lamp body 605. Otherattachment methods such as using set screws is possible for connectingthe output coupling element to the lamp body. By optimizing the gap 140between the output coupling element 120 and the lamp body 650, and thegap 350 between input coupling element 630 and output coupling element120, as well as the dimensions of the input and output coupling elementsand the lamp body one can maximize the transfer of the RF power betweenthe RF source and the bulb 130. This illustration is merely an example,which should not unduly limit the scope of the claims herein. One ofordinary skill in the art would recognize other variations,modifications, and alternatives.

FIG. 4A is a simplified cross-sectional view of the embodiment shown inFIG. 3A. The input coupling element 630 is connected to the lamp body atthe top surface 631 (which is at ground potential 200) and at the otherend is connected to an RF connector 611 through an opening in the lampbody 610. The RF source consists of an oscillator 205 electricallyconnected to the input 212 of the power amplifier 210 and the output ofthe power amplifier 211 is electrically connected to RF connector 611.The amplifier can consist of multiple stages of amplification. The inputcoupling element 630 couples RF energy to the output coupling element120 and the two coupling elements are separated by a coupling gap 350.The output coupling element 120 is connected to the lamp body at thebottom 605 (which is at ground potential 201) and at the other end isconnected to the gas filled vessel (bulb) 130. The top end of the outputcoupling element is shaped to closely receive the gas filled vessel. Inthe case that the output coupling element is made from a solid conductora thin layer of a dielectric material or refractory metal is used as aninterface barrier between the bulb and the output coupling element. Theoutput coupling element is separated from the top portion of the lampbody 650 by a gap 140. By adjusting the dimensions of the input andoutput coupling elements as well as the dimensions of the lamp bodyincluding the size of the gaps 350 and 140, one can maximize thetransfer of the RF power between the RF source and the bulb. The bulb ismade of a suitable material such as quartz or translucent alumina orother transparent or translucent material. The bulb is filled with aninert gas such as Argon or Xenon and a light emitter such as Mercury,Sodium, Dysprosium, Sulfur or a metal halide salt such as IndiumBromide, Scandium Bromide, Thallium Iodide, Holmium Bromide, CesiumIodide or other similar materials (or it can simultaneously containmultiple light emitters). RF energy is coupled capacitively, orinductively, or a combination of inductively and capacitively, by theoutput coupling-element 120 to the bulb 130, ionizing the inert gas andvaporizing the light emitter(s) resulting in intense light emitted fromthe lamp. The majority of the arc of the bulb 115 in this embodiment isnot surrounded by the walls of the lamp body.

FIG. 4B is a simplified drawing of another embodiment of the presentinvention similar to the one shown in FIG. 4A. In this embodiment theinput coupling element 630 and the output coupling element 120 areelectrically connected to ground 200 and 201 through capacitors 330 and340 respectively. The capacitors 330 and 340 are selected to provide lowimpedance connections to ground at the frequency of the RF source. Thecapacitors provide an open circuit at DC.

FIG. 4C illustrates another embodiment of the invention shown in FIG.4A. In this embodiment instead of using an oscillator 205 as the RFsource, a feedback coupling element 635 is added. The feedback couplingelement 635 is closely received by the lamp body 600 through opening 620and as such is not in direct DC electrical contact with the conductivesurface of the lamp body. The shorter feedback coupling element couplesa small amount of RF energy from the lamp body and provides feedback tothe input 212 of an RF power amplifier 210 through an RF connector 621.The output 211 of the RF power amplifier 210 is electrically connectedto the input coupling element 630 through RF connector 611. Inputcoupling element 630 is closely received by the lamp body 600 throughthe opening 610 and as such is not in direct electrical contact with thelamp body at the bottom surface. However, the other end of the inputcoupling element is connected to the lamp body 600 at 631 (which is atground potential 200). The feedback loop between the feedback couplingelement, the RF amplifier, the input coupling element, and the lamp bodyresults in oscillation as long as the amplifier has gain at the resonantfrequency of the lamp body that is larger than the feedback loop lossesand the phase of the feedback loop satisfies steady state oscillationconditions. The RF power from the amplifier is coupled to the outputcoupling element 120 by the input coupling element. The output couplingelement couples the RF energy to the bulb resulting in ionization of theinert gas followed by vaporization of the light emitter(s) which thenresults in light emission from the bulb. This diagram is merely example,which should not unduly limit the scope of the claims herein. One ofordinary skill in the art would recognize other variations,alternatives, and modifications.

FIG. 4D shows another embodiment of the present invention. The lamp issimilar to FIG. 4A except that the top of the gas filled vessel (bulb)is electrically connected to the lamp body 600 (which is at groundpotential) through a top post 180 and wires or straps 170. The post 180can be made from a solid conductor or it can be made from a dielectricmaterial with a conductive coating. In the case that it is made from asolid conductor a thin layer of dielectric material or refractorymaterial can be used as a barrier between the post and the bulb. Thisdiagram is merely an example, which should not unduly limit the scope ofthe claims herein. One of ordinary skill in the art would recognizeother variations, alternatives, and modifications.

FIG. 4E shows another embodiment of the present invention. The lamp issimilar to FIG. 4D except instead of a solid top post 180 anelectrically conductive ring 190 (“halo”) is used that is connected tothe lamp body 600 (which is at ground potential) by wires or straps 170.The conductive ring can be made from metals such as Copper or Aluminumor refractory metals such as Molybdenum or Tungsten. Compared to thesolid top post 180 the “halo” 190 blocks less of the light from the bulband it can be positioned at any point along the length of the bulb tomaximize light output. The “halo” can also be used to control theposition of the arc within the bulb or achieve more concentrated lightfrom a section of the arc. The “halo” can be in contact with the surfaceof the bulb or it can be separated from the bulb by air or a dielectricmaterial. A circular metal ring 190 is depicted, but other shapes may beused. As shown, the ring or ring like structure is substantially freefrom any contact with the bulb and is generally separated by a gapaccording to a specific embodiment. In a specific embodiment, the ringor ring like structure may also be configured with a dielectric layer(e.g., quartz, alumina), which is thin, between the ring or ring likestructure and the bulb. Of course, there can be other variations,modifications, and alternatives.

FIG. 4F shows another embodiment of the present invention. It is similarto the embodiment in FIG. 4A but in this case the lamp body 600, whichsurrounds the input coupling element 630 and output coupling element120, does not necessarily have a cylindrical shape and can take otherforms. The lamp body is filled with air 601 or other gases/fluids or itcan also be a vacuum.

FIG. 5A shows another embodiment of the present invention. It is similarto the embodiment in FIG. 4A but in this case the lamp body 600 isfilled with a dielectric material 701 with a dielectric constant greaterthan 1 such as alumina or quartz instead of air (or vacuum) 601. Thedielectric material has preferably low RF losses. The lamp body isdepicted that is completely filled with dielectric but is it possible tohave a partially filled lamp body. Similar to FIG. 4A most of the arc115 of the bulb 130 is not surrounded by the lamp body.

FIG. 5B shows another embodiment of the present invention. It is similarto the embodiment in FIG. 5A but in this case the lamp body does nothave a “neck” region 650 and part of the gas filled vessel (bulb) 130 isinserted into dielectric material 701 inside the lamp body 600. As aresult the arc 115 inside the bulb is at least partially surrounded bythe lamp body. By using an optically reflective dielectric coating onsurfaces of the bulb inside the lamp body or surrounding those surfacesby a reflective dielectric powder such as alumina powder it is possibleto recover part of the light lost inside the lamp body. Similar to FIG.5A the input coupling element 630 is connected to an RF source at oneend and to the conductive surface 631 of the lamp body at the other endwhich is at ground potential 200. This diagram is merely an example,which should not unduly limit the scope of the claims herein. One ofordinary skill in the art would recognize other variations,alternatives, and modifications.

FIG. 5C shows another embodiment of the present invention. It is similarto the embodiment in FIG. 5B but in this embodiment the bulb 130 isoutside the dielectric material 701 of the lamp body 600 and the arc 115of the bulb is not surrounded by the lamp body. Similar to FIG. 5A theinput coupling element 630 is electrically connected to an RF source atone end through the RF connector 611 and to the conductive surface 631of the lamp body at the other end which is at ground potential 200. Theoutput coupling element 120 is electrically connected to the conductivesurface 605 of the lamp body at one end which is at ground potential201, and connected to the bulb 130 at the other end. Using thisembodiment it is possible to make the lamp body to be much more compact.

FIG. 5D shows another embodiment of the present invention. The lamp issimilar to FIG. 5C except that the top of the gas filled vessel (bulb)is electrically connected to the lamp body 600 (which is at groundpotential) through a top post 180 and wires or straps 170. The post 180can be made from a solid conductor or it can be made from a dielectricmaterial with a conductive coating. In the case that it is made from asolid conductor a thin layer of dielectric material or refractorymaterial can be used as a barrier between the post and the bulb. Thisdiagram is merely an example, which should not unduly limit the scope ofthe claims herein. One of ordinary skill in the art would recognizeother variations, alternatives, and modifications.

FIG. 5E shows another embodiment of the present invention. The lamp issimilar to FIG. 5D except instead of a solid top post 180 anelectrically conductive ring 190 (“halo”) is used that is connected tolamp body 600 (which is at ground potential) by wires or straps 170. Theconductive ring can be made from metals such as Copper or Aluminum orrefractory metals such as Molybdenum or Tungsten. Compared to the solidtop post 180 the “halo” 190 blocks less of the light from the bulb andit can be positioned at any point along the length of the bulb tomaximize light output. The “halo” can also be used to control theposition of the arc within the bulb or achieve more concentrated lightfrom a section of the arc. The “halo” can be in contact with the surfaceof the bulb or it can be separated from the bulb by air or a dielectricmaterial. A circular metal ring 190 is depicted, but other shapes may beused.

FIG. 5F shows another embodiment of the present invention. It is similarto the embodiment in FIG. 5A but in this case the lamp body 600, whichsurrounds the input coupling element 630 and output coupling element120, does not necessarily have a cylindrical shape and can take otherforms. The lamp body is completely or partially filled with a dielectricmaterial 701 with a dielectric constant greater than 1.

FIG. 6A shows another embodiment of the present invention. It is similarto the embodiment in FIG. 4A except that in this case the outputcoupling element 120 is surrounded by a dielectric sleeve 801 made froma material such as quartz. The dielectric sleeve increases thecapacitance in the gap 140 between the output coupling element 120 andthe top section of the lamp body 650 resulting in lowering the resonantfrequency of the lamp body. This diagram is merely an example, whichshould not unduly limit the scope of the claims herein. One of ordinaryskill in the art would recognize other variations, alternatives, andmodifications.

FIG. 6B shows another embodiment of the present invention. It is similarto the embodiment in FIG. 6A but in this case a dielectric sleeve 801surrounds the output coupling element 120, only in the top portion (neckportion) 650 of the lamp body 600.

While the above is a full description of the specific embodiments,various modifications, alternative constructions and equivalents may beused. Therefore, the above description and illustrations should not betaken as limiting the scope of the present invention which is defined bythe appended claims.

1. An electrodeless plasma lamp apparatus comprising: an input couplingelement, the input coupling element having a first input end, a secondinput end, and an input length provided between the first input end andthe second input end; an RF source coupled to the first input end of theinput coupling element; a first ground potential coupled to the secondinput end of the input coupling element; an output coupling elementspatially disposed within a vicinity of the input coupling element, theoutput coupling element comprising a first output end, a second outputend, and an output length provided between the first output end and thesecond output end; a spatial distance configured between the inputlength and the output length; a bulb device coupled to the first outputend of the output coupling element; and a second ground potentialcoupled to the second output end of the output coupling element.
 2. Theapparatus of claim 1 wherein the first ground potential and the secondground potential is the same ground potential and wherein the RF sourceis electrically connected to the first input end of the input couplingelement.
 3. The apparatus of claim 1 wherein the spatial distanceseparates the input coupling element from the output coupling element.4. The apparatus of claim 1 wherein the input coupling element and theoutput coupling element are configured in a parallel arrangement.
 5. Theapparatus of claim 1 wherein the RF source comprises an oscillator andone or more amplifiers.
 6. The apparatus of claim 1 further comprising afirst capacitor configured between the first ground potential and thesecond input end of the input coupling element.
 7. The apparatus ofclaim 6 further comprising a second capacitor configured between thesecond ground potential and the second output end of the output couplingelement.
 8. The apparatus of claim 1 further comprising a secondcapacitor configured between the second ground potential and the secondoutput end of the output coupling element.
 9. The apparatus of claim 1further comprising a first inductive coil device configured between thefirst ground potential and the first input end of the input couplingelement.
 10. The apparatus of claim 9 further comprising a secondinductive coil device configured between the second ground potential andthe second output end of the output coupling element.
 11. The apparatusof claim 1 further comprising a second inductive coil device configuredbetween the second ground potential and the second output end of theoutput coupling element.
 12. The apparatus of claim 1 further comprisinga first inductive coil device and a first capacitor device configuredbetween the first ground potential and the first input end of the inputcoupling element.
 13. The apparatus of claim 12 further comprising asecond inductive coil device and a second capacitor device configuredbetween the second ground potential and the second output end of theoutput coupling element.
 14. The apparatus of claim 1 further comprisinga second inductive coil device and a second capacitor device configuredbetween the second ground potential and the second output end of theoutput coupling element.
 15. An electrodeless plasma lamp apparatuscomprising: an input coupling element, the input coupling element havinga first input end, a second input end, and an input length providedbetween the first input end and the second input end; an RF sourcecoupled to the first input end of the input coupling element; a firstground potential coupled to the second input end of the input couplingelement; an output coupling element spatially disposed within a vicinityof the input coupling element, the output coupling element comprising afirst output end, a second output end, and an output length providedbetween the first output end and the second output end; a spatialdistance configured between the input length and the output length; adielectric fill material or materials configured to enclose one or moreportions of the input coupling element, the output coupling element, andthe spatial distance between the input coupling element and the outputcoupling element; a bulb device coupled to the first output end of theoutput coupling element; and a second ground potential coupled to thesecond output end of the output coupling element.
 16. The apparatus ofclaim 15 wherein the first ground potential and the second groundpotential is the same ground potential.
 17. The apparatus of claim 15wherein the spatial distance separates the input coupling element fromthe output coupling element.
 18. The apparatus of claim 15 wherein theinput coupling element and the output coupling element are configured ina parallel arrangement.
 19. The apparatus of claim 15 wherein the RFsource comprises an oscillator and one or more amplifiers.
 20. Theapparatus of claim 15 further comprising a first capacitor configuredbetween the first ground potential and the second input end of the inputcoupling element.
 21. The apparatus of claim 20 further comprising asecond capacitor configured between the second ground potential and thesecond output end of the output coupling element.
 22. The apparatus ofclaim 15 further comprising a second capacitor configured between thesecond ground potential and the second output end of the output couplingelement.
 23. The apparatus of claim 15 further comprising a firstinductive coil device configured between the first ground potential andthe first input end of the input coupling element.
 24. The apparatus ofclaim 23 further comprising a second inductive coil device configuredbetween the second ground potential and the second output end of theoutput coupling element.
 25. The apparatus of claim 15 furthercomprising a second inductive coil device configured between the secondground potential and the second output end of the output couplingelement.
 26. The apparatus of claim 15 further comprising a firstinductive coil device and a first capacitor device configured betweenthe first ground potential and the first input end of the input couplingelement.
 27. The apparatus of claim 26 further comprising a secondinductive coil device and a second capacitor device configured betweenthe second ground potential and the second output end of the outputcoupling element.
 28. The apparatus of claim 15 further comprising asecond inductive coil device and a second capacitor device configuredbetween the second ground potential and the second output end of theoutput coupling element.
 29. The apparatus of claim 15 wherein thedielectric fill material comprises alumina.
 30. The apparatus of claim15 wherein the dielectric fill material comprises at least silicondioxide or quartz.
 31. The apparatus of claim 15 wherein the dielectricfill material comprises silicon nitride.
 32. The apparatus of claim 15wherein the dielectric fill material is characterized by a loss tangentof 0.01 and less.
 33. The apparatus of claim 15 wherein the dielectricfill material is characterized by a loss tangent of 0.02 and less. 34.An electrodeless plasma lamp apparatus comprising: an input couplingelement, the input coupling element having a first input end, a secondinput end, and an input length provided between the first input end andthe second input end; an RF source coupled to the first input end of theinput coupling element; a first ground potential coupled to the secondinput end of the input coupling element; an output coupling elementspatially disposed within a vicinity of the input coupling element, theoutput coupling element comprising a first output end, a second outputend, and an output length provided between the first output end and thesecond output end; a spatial distance configured between the inputlength and the output length; a dielectric fill material or materialsconfigured to enclose one or more portions of the input couplingelement, the output coupling element, and the spatial distance betweenthe input coupling element and the output coupling element; and a bulbdevice coupled to the first output end of the output coupling element.35. The apparatus of claim 34 wherein the dielectric fill materialcomprises alumina.
 36. The apparatus of claim 34 wherein the dielectricfill material comprises at least silicon dioxide or quartz.
 37. Theapparatus of claim 34 wherein the dielectric fill material comprisessilicon nitride.
 38. The apparatus of claim 34 wherein the dielectricfill material is characterized by a loss tangent of 0.01 and less. 39.The apparatus of claim 34 wherein the dielectric fill material ischaracterized by a loss tangent of 0.02 and less.
 40. The apparatus ofclaim 34 wherein the dielectric fill material is configured partiallyaround one or more portions of the bulb device.
 41. An electrodelessplasma lamp apparatus comprising: an input coupling element, the inputcoupling element having a first input end, a second input end, and aninput length provided between the first input end and the second inputend; an RF source coupled to the first input end of the input couplingelement; a first ground potential coupled to the second input end of theinput coupling element; an output coupling element spatially disposedwithin a vicinity of the input coupling element, the output couplingelement comprising a first output end, a second output end, and anoutput length provided between the first output end and the secondoutput end; a spatial distance configured between the input length andthe output length; a bulb device coupled to the first output end of theoutput coupling element; a top coupling element coupled to the other endof bulb device; and a second ground potential coupled to the secondoutput end of the output coupling element.
 42. The apparatus of claim 41wherein the first ground potential and the second ground potential isthe same ground potential.
 43. The apparatus of claim 41 wherein thespatial distance separates the input coupling element from the outputcoupling element.
 44. The apparatus of claim 41 wherein the inputcoupling element and the output coupling element are configured in aparallel arrangement.
 45. The apparatus of claim 41 wherein the RFsource comprises an oscillator and one or more amplifiers.
 46. Theapparatus of claim 41 further comprising a first capacitor configuredbetween the first ground potential and the second input end of the inputcoupling element.
 47. The apparatus of claim 46 further comprising asecond capacitor configured between the second ground potential and thesecond output end of the output coupling element.
 48. The apparatus ofclaim 41 further comprising a second capacitor configured between thesecond ground potential and the second output end of the output couplingelement.
 49. The apparatus of claim 41 further comprising a firstinductive coil device configured between the first ground potential andthe first input end of the input coupling element.
 50. The apparatus ofclaim 49 further comprising a second inductive coil device configuredbetween the second ground potential and the second output end of theoutput coupling element.
 51. The apparatus of claim 41 furthercomprising a second inductive coil device configured between the secondground potential and the second output end of the output couplingelement.
 52. The apparatus of claim 41 further comprising a firstinductive coil device and a first capacitor device configured betweenthe first ground potential and the first input end of the input couplingelement.
 53. The apparatus of claim 52 further comprising a secondinductive coil device and a second capacitor device configured betweenthe second ground potential and the second output end of the outputcoupling element.
 54. The apparatus of claim 41 further comprising asecond inductive coil device and a second capacitor device configuredbetween the second ground potential and the second output end of theoutput coupling element.
 55. The apparatus of claim 41 furthercomprising a dielectric fill material or materials configured to encloseone or more portions of the input coupling element, the output couplingelement, and the spatial distance between the input coupling element andthe output coupling element.
 56. The apparatus of claim 55 wherein thedielectric fill material comprises alumina.
 57. The apparatus of claim55 wherein the dielectric fill material comprises silicon dioxide. 58.The apparatus of claim 55 wherein the dielectric fill material comprisessilicon nitride.
 59. The apparatus of claim 55 wherein the dielectricfill material is characterized by a loss tangent of 0.01 and less. 60.The apparatus of claim 55 wherein the dielectric fill material ischaracterized by a loss tangent of 0.02 and less.
 61. The apparatus ofclaim 41 wherein the top coupling element is configured to a groundpotential.
 62. The apparatus of claim 41 wherein the top couplingelement is grounded.
 63. An electrodeless plasma lamp apparatuscomprising: an input coupling element, the input coupling element havinga first input end, a second input end, and an input length providedbetween the first input end and the second input end; an RF sourcecoupled to the first input end of the input coupling element; a firstground potential coupled to the second input end of the input couplingelement; an output coupling element spatially disposed within a vicinityof the input coupling element, the output coupling element comprising afirst output end, a second output end, and an output length providedbetween the first output end and the second output end; a spatialdistance configured between the input length and the output length; abulb device coupled to the first output end of the output couplingelement; a top coupling element coupled to the bulb device and isconfigured as an annular structure, the annular structure being freefrom physical contact with any portion of the bulb device; and a secondground potential coupled to the second output end of the output couplingelement.
 64. The apparatus of claim 63 wherein the first groundpotential and the second ground potential is the same ground potential.65. The apparatus of claim 63 wherein the spatial distance separates theinput coupling element from the output coupling element.
 66. Theapparatus of claim 63 wherein the input coupling element and the outputcoupling element are configured in a parallel arrangement.
 67. Theapparatus of claim 63 wherein the RF source comprises an oscillator andone or more amplifiers.
 68. The apparatus of claim 63 further comprisinga first capacitor configured between the first ground potential and thesecond input end of the input coupling element.
 69. The apparatus ofclaim 68 further comprising a second capacitor configured between thesecond ground potential and the second output end of the output couplingelement.
 70. The apparatus of claim 63 further comprising a secondcapacitor configured between the second ground potential and the secondoutput end of the output coupling element.
 71. The apparatus of claim 63further comprising a first inductive coil device configured between thefirst ground potential and the first input end of the input couplingelement.
 72. The apparatus of claim 71 further comprising a secondinductive coil device configured between the second ground potential andthe second output end of the output coupling element.
 73. The apparatusof claim 63 further comprising a second inductive coil device configuredbetween the second ground potential and the second output end of theoutput coupling element.
 74. The apparatus of claim 63 furthercomprising a first inductive coil device and a first capacitor deviceconfigured between the first ground potential and the first input end ofthe input coupling element.
 75. The apparatus of claim 74 furthercomprising a second inductive coil device and a second capacitor deviceconfigured between the second ground potential and the second output endof the output coupling element.
 76. The apparatus of claim 63 furthercomprising a second inductive coil device and a second capacitor deviceconfigured between the second ground potential and the second output endof the output coupling element.
 77. The apparatus of claim 63 furthercomprising a dielectric fill material or materials configured to encloseone or more portions of the input coupling element, the output couplingelement, and the spatial distance between the input coupling element andthe output coupling element.
 78. The apparatus of claim 77 wherein thedielectric fill material comprises alumina.
 79. The apparatus of claim77 wherein the dielectric fill material comprises silicon dioxide. 80.The apparatus of claim 77 wherein the dielectric fill material comprisessilicon nitride.
 81. The apparatus of claim 77 wherein the dielectricfill material is characterized by a loss tangent of 0.01 and less. 82.The apparatus of claim 77 wherein the dielectric fill material ischaracterized by a loss tangent of 0.02 and less.
 83. The apparatus ofclaim 63 wherein the top coupling element is configured to a groundpotential.
 84. The apparatus of claim 63 wherein the top couplingelement is grounded.
 85. The apparatus of claim 63 wherein the annularstructure is a ring-like structure configured substantially free fromcontact with an outer region of the bulb device
 86. The apparatus ofclaim 63 wherein the annular structure is a ring-like structureconfigured substantially free from contact with an outer region of thebulb device; and further comprises at least a dielectric materialdisposed between the ring like structure and the outer region of thebulb device.
 87. An electrodeless plasma lamp apparatus comprising: aninput coupling element, the input coupling element having a first inputend, a second input end, and an input length provided between the firstinput end and the second input end, the first input end being coupled toan RF source and the second input end being coupled to a first groundpotential; an output coupling element spatially disposed within avicinity of the input coupling element, the output coupling elementcomprising a first output end, a second output end, and an output lengthprovided between the first output end and the second output end, thefirst output end being coupled to a bulb device configured to emitelectro-magnetic radiation, and the second output end being coupled to asecond ground potential; and a spatial distance configured between theinput length of the input coupling element and the output length of theoutput coupling element.